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  • richardmitnick 4:58 pm on October 15, 2018 Permalink | Reply
    Tags: , , , , , Fermi Gamma Ray Space Telescope, , ,   

    From SLAC National Accelerator Lab: “Missing gamma-ray blobs shed new light on dark matter, cosmic magnetism” 

    From SLAC National Accelerator Lab

    October 15, 2018
    Manuel Gnida

    Astrophysicists use a catalog of extended gamma-ray sources spotted by Fermi spacecraft to home in on mysterious properties of deep space.

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    Extended gamma-ray sources (circled areas) identified in data taken with the Large Area Telescope on NASA’s Fermi spacecraft. (Matthew Wood/Fermi-LAT collaboration)

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    When astrophysicists look at the gamma-ray glow from a galaxy outside our own, all they typically see is a small spot because the galaxy is extremely far away. So, when a galaxy appears as an extended blob, something extraordinary must be going on that could help researchers better understand the properties of deep space.

    Now, scientists, including researchers from the Department of Energy’s SLAC National Accelerator Laboratory, have compiled the most detailed catalog of such blobs using eight years of data collected with the Large Area Telescope (LAT) on NASA’s Fermi Gamma-Ray Space Telescope. The blobs, including 19 gamma-ray sources that weren’t known to be extended before, provide crucial information on how stars are born, how they die, and how galaxies spew out matter trillions of miles into space.

    Intriguingly, though, it was the cosmic regions where they didn’t find blobs that shed new light on two particularly mysterious ingredients of the universe: dark matter – an invisible form of matter six times more prevalent than regular matter – and the magnetic field that pervades the space between galaxies and whose origin is unknown.

    “These data are very exciting because they allow us to study some of the most fundamental processes in the universe, and they could potentially lead us to discover completely new physics,” says NASA scientist Regina Caputo, one of the leaders of the recent study by the international Fermi-LAT collaboration, which was published in The Astrophysical Journal.

    One of the things the researchers looked for were gamma-ray blobs associated with companion galaxies orbiting our Milky Way.

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    Researchers have discovered a set of possible dwarf satellite galaxies orbiting the Milky Way. The new objects (red dots) were detected in the new sky area (gray transparent area) covered by the Dark Energy Survey. Scientists have seen about two dozen dwarf galaxies (blue dots) before. They are the smallest known galaxy structures and may hold the key to understanding unseen dark matter, which accounts for about 85 percent of all matter in the universe but whose nature is unknown. The zoom-in region shows an image of the stars that likely belong to one of the dwarf galaxy candidates. (Kavli Institute for Particle Astrophysics and Cosmology/SLAC National Accelerator Laboratory/Fermi National Accelerator Laboratory/Dark Energy Survey/Infrared Processing and Analysis Center/California Institute of Technology/University of Massachusetts)

    Since the faintest of these satellites contain very few stars, they are thought to be held together by dark matter.

    Scientists believe dark matter could be made of particles called WIMPs, which would emit gamma rays when they collide and destroy each other. A gamma-ray blob signal coming from an ultrafaint satellite galaxy would be a strong hint that WIMPS exist.

    “Our simulations of galaxy formation predict that there should be more satellite galaxies than those we’ve been able to detect in optical surveys,” Caputo says. “Some of them could be so faint that we might only be able to see them if they produced gamma rays due to dark matter annihilation.”

    In the new study, the Fermi-LAT researchers searched for gamma-ray blobs associated with those predicted satellite galaxies. They didn’t find any. But even the fact that they came up empty-handed is an important result: It will allow them, in future studies, to define the distribution of dark matter in Milky Way satellites and the likelihood that WIMPs produce gamma rays. It also provides new input for models of galaxy evolution.

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    The Small Magellanic Cloud (SMC) is the second-largest satellite galaxy orbiting our Milky Way. The image superimposes a photograph of the SMC with one-half of a model of its dark matter. Lighter colors indicate greater density and show a strong concentration of dark matter toward the SMC’s center. (Regina Caputo/NASA; Axel Mellinger/Central Michigan University)

    Small Magellanic Cloud. NASA/ESA Hubble and ESO/Digitized Sky Survey 2

    Faint cosmic magnetism

    The researchers also used their data to obtain more information on the strength of the magnetic field between galaxies, which they hope will be an important puzzle piece in determining the origin of the field.

    For this part of the study, the team looked at blazars – active galaxies that spit high-speed jets of plasma far into space. The Fermi spacecraft can detect gamma rays associated with jets that point in the direction of the Earth.

    Blazars appear as point-like sources, but a mechanism involving the intergalactic magnetic field could potentially make them look like extended sources, says Manuel Meyer, a Humboldt fellow at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) and another lead author of the study.


    Manuel Meyer, Humboldt fellow at the Kavli Institute for Particle Astrophysics and Cosmology, explains a process involving the intergalactic magnetic field that could potentially make active galaxies known as blazars appear as extended gamma-ray sources in data taken with the Large Area Telescope onboard NASA’s Fermi mission. (Manuel Meyer/Kavli Institute for Particle Astrophysics and Cosmology)

    The researchers didn’t find any blobs associated with blazars. Again, this no-show was valuable information: It allowed the team to calculate that the magnetic field is at least a tenth of a millionth billionth as strong as Earth’s magnetic field. The magnetic field’s upper limit – a billion times weaker than Earth’s field – was already known.

    The intergalactic field is stronger than the researchers had expected, Meyer says, and this new information might help them find out whether it stems from material spilled into space in recent times or whether it was created in processes that occurred in earlier cosmic history.

    The cosmic magnetism could also have ties to dark matter. In an alternative to the WIMP model, dark matter is proposed to be made of lighter particles called axions that could emerge from gamma rays (and convert back into them) in the presence of a magnetic field. “For that to occur, the field strength would need to be closer to its upper limit, though,” Meyer says. “It’s definitely interesting to take this mechanism into account in our dark matter studies, and we’re doing this right now within the Fermi-LAT collaboration.”

    NASA’s Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy Office of Science and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States. The Fermi mission recently celebrated its 10th anniversary. A number of SLAC researchers are members of the international Fermi-LAT collaboration. SLAC assembled the LAT and hosts the operations center that processes LAT data. The new analysis benefitted from a data analysis package, initially developed by KIPAC researcher Matthew Wood, that automates common analysis tasks. KIPAC is a joint institute of SLAC and Stanford University.

    See the full article here .


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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
  • richardmitnick 2:40 pm on July 15, 2018 Permalink | Reply
    Tags: , , , , , Fermi Gamma Ray Space Telescope, , , ,   

    From Spaceflight Insider: “Fermi Telescope discovers neutrino’s origin as supermassive black hole” 

    1

    From Spaceflight Insider

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    A cosmic neutrino detected by NASA’s Fermi Gamma-ray Space Telescope was found to have originated in a gamma ray emitted by a supermassive black hole 3.7 billion light years away at the center of a galaxy in the constellation Orion.

    The discovery, made by an international team of scientists, marks the first time a high-energy neutrino from beyond the Milky Way has been traced to its place of origin as well as the furthest any neutrino has been known to travel.

    Neutrinos are high-energy, hard-to-catch particles likely produced in powerful cosmic events, such as supermassive black holes actively devouring matter and galaxy mergers. Because they travel at nearly the speed of light and do not interact with other matter, they are capable of traversing billions of light years.

    By studying neutrinos, scientists gain insight into the processes that drive powerful cosmic events, including supernovae and black holes.

    Gamma rays are the brightest and most energetic form of light, which is why scientists use them to trace the sources of neutrinos and cosmic rays.

    “The most extreme cosmic explosions produce gravitational waves, and the most extreme cosmic accelerators produce high-energy neutrinos and cosmic rays,” explained Regina Caputo of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and analysis coordinator for the Fermi Large Area Telescope Collaboration. “Through Fermi, gamma rays are providing a bridge to each of these new cosmic signals.”

    Scientists found this particular neutrino on September 22, 2017, using the National Science Foundation‘s (NSF) IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station. They then traced the neutrino to its origin in a gamma ray blast within the distant supermassive black hole using Fermi.[ https://sciencesprings.wordpress.com/2018/07/13/the-great-neutrino-catch-a-bunch-of-articles/ ]

    “Again, Fermi has helped make another giant leap in a growing field we call multimessenger astronomy. Neutrinos and gravitational waves deliver new kinds of information about the most extreme environments in the universe. But to understand what they’re telling us, we need to connect them to the ‘messenger’ astronomers know best–light,” emphasized Paul Hertz, director of NASA’s Astrophysics Division in Washington, DC.

    IceCube tracked the neutrino, which hit Antarctica with 300 trillion electron volts. Its extremely high energy level meant it likely came from beyond our solar system. Its galaxy of origin, with which scientists are familiar, is a blazar, a galaxy with an extremely bright and active central supermassive black hole that blasts out jets of particles in opposite directions at nearly the speed of light.

    Blazars have several million to several billion times the mass of our Sun. Scientists find them when one of the jets they emit travels in the direction of Earth.

    Yasuyuki Tanaka of Japan’s Hiroshima University was the first scientist to link the neutrino to a specific blazar known as TXS 0506+056, which has recently shown increased activity. Fermi keeps track of approximately 2,000 blazars.

    Followup observations of TXS 0506 were conducted with the Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) NASA’s Neil Gehrels Swift Observatory, and various other observatories.[See above link to previous post Bunch of Articles]

    Two papers on the discovery have been published here and here in the journal Science.

    See the full article here .

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    Please help promote STEM in your local schools.

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    SpaceFlight Insider reports on events taking place within the aerospace industry. With our team of writers and photographers, we provide an “insider’s” view of all aspects of space exploration efforts. We go so far as to take their questions directly to those officials within NASA and other space-related organizations. At SpaceFlight Insider, the “insider” is not anyone on our team, but our readers.

    Our team has decades of experience covering the space program and we are focused on providing you with the absolute latest on all things space. SpaceFlight Insider is comprised of individuals located in the United States, Europe, South America and Canada. Most of them are volunteers, hard-working space enthusiasts who freely give their time to share the thrill of space exploration with the world.

     
  • richardmitnick 5:15 pm on December 28, 2017 Permalink | Reply
    Tags: , , , , CRAND-cosmic ray albedo neutron decay, CSSWE-Colorado Student Space Weather Experiment, CU Boulder’s Laboratory for Atmospheric and Space Physics, , , Fermi Gamma Ray Space Telescope, Mystery About Earth’s Van Allen Belts Solved by Researchers   

    From Edgy: “Mystery About Earth’s Van Allen Belts Solved by Researchers” 

    Edgy Labs

    1

    December 28, 2017
    Chelle Ann Fuertes

    Researchers from Colorado have finally solved a decades-long mystery surrounding the Van Allen Belts.

    With the help of a tiny orbiting satellite, researchers from the University of Colorado Boulder were able to shed light on the 60-year-old mystery shrouding Earth’s Van Allen belts. In a study published in the journal Nature, the team investigated the source of the energetic and potentially damaging electrons found in our planet’s inner radiation belt, near its inner edge.

    If you’re not familiar with it, the Van Allen Belts are two large belts of radiation surrounding Earth, a so-called area of energetic particles, and they are supposedly held in place by our planet’s magnetic field. Apparently, these belts protect us from some of space’s most dangerous radiation by trapping charged particles within its region.

    Through the years, space scientists studied these belts in an effort to answer some more complex questions about its existence such as what happens when particles from our sun hit the belts during a geomagnetic storm. Researchers admit that more work needs to be carried out as many previous observations of the belts were done only with electrons at a small range of energy levels.

    Uncovering the Van Allen Belts’ Source of Energetic Particles

    The study, led by Professor Xinlin Li of CU Boulder’s Laboratory for Atmospheric and Space Physics (LASP), was able to solve one of the many mysteries of the Van Allen belts: the source of its energetic and potentially harmful particles.

    The study indicates that the energetic electrons found in our planet’s inner radiation belt, particularly near the inner edge, originate from supernovae. It appears that during a process known as “cosmic ray albedo neutron decay” (CRAND), the cosmic rays from exploding stars entering Earth’s atmosphere collide with neutral atoms. These collisions form a so-called splash which in turn produces charged particles, including electrons, that are being kept in place by Earth’s magnetic fields.


    Evidence found for gamma rays by the Fermi Gamma Ray Space Telescope

    NASA/Fermi LAT

    NASA/Fermi Gamma Ray Space Telescope

    “We are reporting the first direct detection of these energetic electrons near the inner edge of Earth’s radiation belt,” Li, a professor in CU-Boulder’s Aerospace Engineering Sciences department, said.

    It was said that soon after the discovery of the Van Allen belts in the late 1950s, both Russian and American scientists concluded that CRAND was most likely the reason behind the high-energy protons trapped in Earth’s magnetic field. However, no one was able to successfully detect the electron counterparts that should have been produced during the neutron decay process.

    Thanks to a CubeSat known as the Colorado Student Space Weather Experiment (CSSWE), the source of the once-undetectable energetic electrons were finally discovered. CubeSats are usually small satellites about the size of a loaf of bread.

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    The CubeSat CSSWE before going into space orbit to observe the Van Allen belts | UC Boulder

    CSSWE in particular housed a small, energetic particle telescope, the Relativistic, Electron and Proton Telescope, used to measure the flux of solar energetic protons and Earth’s radiation belt electrons. It was launched in 2012 on an Atlas V rocket.

    “This is really a beautiful result and a big insight derived from a remarkably inexpensive student satellite, illustrating that good things can come in small packages,” Daniel Baker, co-author of the study, said. “It’s a major discovery that has been there all along, a demonstration that Yogi Berra was correct when he remarked ‘You can observe a lot just by looking.’”

    The discovery of the source of energetic electrons in the Van Allen belts is beneficial in creating better space suits and ships for future space missions.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
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